Two of the recent books in the Methods in Molecular Biology series, Yeast Prools and Pichia Prools, have been narrowly focused on yeasts and, in the latter case, particular species of yeasts. Food Microbiology Pro- cols, of necessity, covers a very wide range of microorganisms. Our book treats four categories of microorganisms affecting foods: (1) Spoilage organisms; (2) pathogens; (3) microorganisms in fermented foods; and (4) microorganisms p- ducing metabolites that affect the flavor or nutritive value of foods. Detailed information is given on each of these categories. There are several chapters devoted to the microorganisms associated with fermented foods: these are of increasing importance in food microbiology, and include one bacteriophage that kills the lactic acid bacteria involved in the manufacture of different foods—cottage cheese, yogurt, sauerkraut, and many others. The other nine chapters give procedures for the maintenance of lactic acid bacteria, the isolation of plasmid and genomic DNA from species of Lac- bacillus, determination of the proteolytic activity of lactic acid bacteria, det- mination of bacteriocins, and other important topics.